The present invention relates to a simulated moving bed apparatus. More particularly, this invention relates to a simulated moving bed apparatus that can be operated stably, and moreover can regain stable functioning without troubles shortly after operating conditions are changed. The apparatus can separate plural components with high separation efficiency, while it can be designed to have an ultra small size.
A conventional simulated moving bed apparatus comprises plural unit packed beds, which are also called unit columns, packed with a filler, said plural unit packed beds having a fore-end and a back-end, said back-end of one bed being connected with said fore-end of the next bed via a conduit and thus said unit packed beds being connected in series with each other to form an endless circulation passage, through which fluid is circulated unidirectionally, wherein a feedstock mixture and an eluent are introduced into said circulation passage, and at the same time a liquid mixture containing a substance separated from the filler and another liquid mixture containing other substances are drawn out from said circulation passage; and each of said unit packed beds being provided with an introducing port for introducing the eluent, a draw-out port for drawing out a strongly adsorbed substance, which is called an extract, an introducing port for introducing the feedstock mixture, and a draw-out port for drawing out a weakly adsorbed substance, which is called a raffinate, wherein one of said eluent introducing ports, one of said extract draw-out ports, one of said feedstock mixture introducing ports and one of said raffinate draw-out ports are on in this order along the direction of fluid circulation, and said working positions of the ports are successively shifted in the direction of fluid circulation intermittently with a switching device.
Conventional simulated moving bed apparatuses having such a structure were adapted to low-pressure operation. They were used for large-scale separation of sugar. Recently, highly efficient fillers that have a small particle diameter and therefore are capable of carrying out accurate separation have been developed. With a simulated moving bed apparatus of which columns are packed with such highly efficient fillers was started carrying out, under high pressure, separations including optical resolution of, for example, medicines.
As the apparatus has become widely used, are desired ultra-micro simulated moving bed apparatuses used for obtaining basic data for scaling up or for carrying out a separation of a small amount sample. For screening medicines and carrying out pre-clinical examinations, there is a large demand for small-amount sample separation apparatuses.
When a conventional apparatus having the aforementioned structure is simply miniaturized, however, the content volume of the space in the system (Vs) becomes large compared with the content volume of the columns (Vc). This problem results from the fact that it is difficult to miniaturize conventional pumps and switching valves in proportion to the reduction of the whole apparatus size, with the strength against the high pressure being maintained. Another reason is that there is a limit to the minimization of the inner diameter of the conduits, because the inner diameter has to be large enough to prevent the conduits from blocking. For example, in a comparatively small-sized simulated moving bed apparatus employing unit columns each of which has a content volume of about 1,000 cm3, Vs/Vc is approximately 5%. On the other hand, if a simulated moving bed apparatus provided with unit columns each of which has a content volume of about 10 cm3 is made under the design idea of simply scaling down the apparatus size, Vs/Vc is several tens percent. When the value of Vs/Vc is large, the separation efficiency of a sample is lowered due to diffusion of the target substance inside the system. Besides, the operation stability of the simulated moving bed apparatus is reduced.
In order to minimize Vs in small-sized simulated moving bed apparatuses have often been used rotary valves as a switching device. When a rotary valve is changed over, however, fluctuation in the pressure in the system occurs. When a simulated moving bed apparatus is operated under a high pressure, such fluctuation in the system""s pressure is a fatal cause of obstructing the stable operation. So, in conventional apparatuses pressure dampers were used to absorb such pressure fluctuation. For ultra-micro simulated moving bed apparatuses that tend to have a large Vs, however, it is difficult to employ such pressure dampers from the viewpoint of minimizing Vs.
As a pump that is incorporated in the simulated moving bed apparatus was often used a diaphragm pump, which has a drawback of causing a pulsation. For overcoming this problem diaphragm pumps with 3 or more heads have to be employed. Although this employment solves the pulsation, it creates another problem; it makes Vs larger. Also, the incorporation of a diaphragm pump into an ultra-micro simulated moving bed apparatus provided with unit columns each of which has a content volume of about 10 cm3 is in itself technically difficult.
Although the use of conduits having a small inner diameter might theoretically be considered to make an ultra-micro apparatus, it has a limit as a realistic technology.
The object of this invention is to solve the aforementioned problems. The objective of the invention is to provide an ultra-micro-sized simulated moving bed apparatus that exhibits acceptable operation stability under practical operating conditions, can regain a stable functioning shortly after the operation conditions are changed, and is capable of separating components with high purity.
Another objective of the invention is to provide an ultra-micro-sized simulated moving bed apparatus that can separate the components with high purity when the amount of the sample is small, exhibit acceptable operation stability under practical operating conditions, regain a stable functioning shortly after the operation conditions are changed, and does not give pulsation to the circulating fluid.
A further objective of the invention is to provide an ultra-micro-sized simulated moving bed apparatus that can separate the components with high purity when the amount of the sample is small, and has such a size as to be able to be placed on an experiment table in a laboratory and convenient for obtaining basic data necessary for scaling up.
This invention provides a simulated moving bed apparatus which comprises:
a circulation passage formed by plural unit columns that are connected in series to each other endlessly via a conduit for allowing unidirectional circulation of a circulation fluid through the connected filler columns by a circulation pump;
an eluent feeding cul-de-sac passage for feeding an eluent to said circulation passage;
a feedstock mixture feeding cul-de-sac passage for feeding a feedstock mixture to said circulation passage;
a raffinate draw-out cul-de-sac passage for drawing out a raffinate from said circulation passage;
an extract draw-out cul-de-sac passage for drawing out an extract from said circulation passage;
plural valve devices, each comprising an eluent valve which opens or closes a first communication passage that connects said eluent feeding cul-de-sac passage with said circulation passage, an extract valve which opens or closes a second communication passage that connects said extract draw-out cul-de-sac passage with said circulation passage, a feedstock mixture valve which opens or closes a third communication passage that connects said feedstock mixture feeding cul-de-sac passage with said circulation passage, and a raffinate valve which opens or closes a fourth communication passage that connects said raffinate draw-out cul-de-sac passage with said circulation passage, wherein each of said unit columns is provided with each of said valve devices; and
a control device which controls opening and closing motions of said feedstock mixture valve, said eluent valve, said extract valve and said raffinate valve so that the position for introducing said eluent, the position for drawing out said extract, the position for introducing said feedstock mixture and the position for drawing out said raffinate are successively moved in the direction of the fluid flow intermittently.
In the simulated moving bed apparatus, said plural valve devices are each provided with fluid passages connected with said first, second, third and fourth communication passages, wherein said fluid passages form part of said circulation passage.
In the simulated moving bed apparatus, said valve devices are incorporated into one or more units so that all of the valve devices communicate with the same one eluent feeding cul-de-sac passage, one feedstock mixture feeding cul-de-sac passage, one raffinate draw-out cul-de-sac passage and one extract draw-out cul-de-sac passage.
In the simulated moving bed apparatus, said plural valve devices are grouped and incorporated into two units so that every other valve device along said circulation passage is grouped one of the two units, wherein all of the valve devices in the same group communicate with the same one eluent feeding cul-de-sac passage, one feedstock mixture feeding cul-de-sac passage, one raffinate draw-out cul-de-sac passage and one extract draw-out cul-de-sac passage.
In the simulated moving bed apparatus, said each of valve devices comprises an eluent passage that forms a part of said eluent feeding cul-de-sac passage, an extract passage that forms a part of said extract draw-out cul-de-sac passage, a feedstock mixture passage that forms a part of said feedstock mixture feeding cul-de-sac passage and a raffinate passage that forms a part of raffinate draw-out cul-de-sac passage; and
said eluent valve comprises a first valve element that is capable of opening and closing said first communication passage and does not close said eluent passage when said first communication passage is closed, said extract valve comprises a second valve element that is capable of opening and closing said second communication passage and does not close said extract passage when said second communication passage is closed, said feedstock mixture valve comprises a third valve element that is capable of opening and closing said third communication passage and does not close said feedstock mixture passage when said third communication passage is closed, and said raffinate valve comprises a fourth valve element that is capable of opening and closing said fourth communication passage and does not close said raffinate passage when said fourth communication passage is closed.
In the simulated moving bed apparatus, each of said valve devices includes:
a first hollow cylinder communicating with said first communication passage and said eluent passage respectively, and a first plunger sealingly fitting into said first hollow cylinder, said first plunger being movable backward and forward therein;
a second hollow cylinder communicating with said second communication passage and said extract passage respectively, and a second plunger sealingly fitting into said second hollow cylinder, said second plunger being movable backward and forward therein;
a third hollow cylinder communicating with said third communication passage and said feedstock mixture passage respectively, and a third plunger sealingly fitting into said third hollow cylinder, said third plunger being movable backward and forward therein; and
a fourth hollow cylinder communicating with said fourth communication passage and said raffinate passage respectively, and a fourth plunger sealingly fitting into said fourth hollow cylinder, said fourth plunger being movable backward and forward therein.
In the simulated moving bed apparatus, said circulation pump is a pump for circulating the circulation fluid and the amount of flowing fluid through said pump can be set; said eluent feeding cul-de-sac passage is connected with an eluent pump for feeding an eluent and of which amount of outflowing said eluent can be set; said extract draw-out passage is connected with an extract pump for drawing out an extract and of which amount of inflowing the extract can be set; said feedstock mixture feeding cul-de-sac passage is connected with a feedstock mixture pump for feeding a feedstock mixture and of which amount of outflowing the feedstock mixture can be set; and said raffinate draw-out passage is connected with a raffinate pump for drawing out a raffinate and of which amount of inflowing the raffinate can be set.
In the simulated moving bed apparatus, said circulation pump, said eluent pump, said extract pump, said feed stock mixture pump and said raffinate pump are double plunger pumps.
In the simulated moving bed apparatus, said apparatus measures 1 m or less in height, 1 m or less in width, and 1 m or less in length.